1. Field of the Invention
The present invention relates to a parallax compensating device for the view finder of a camera, and more particularly to a parallax compensating device for use in a camera which incorporates a supplementary lens, such as a close-up lens, which is movable into the optical path of the regular lens in order to change the focal length thereof. Thus, the present invention relates to cameras in which a supplementary lens can be selectively put into combined use with a picture-taking lens by the operation of a selector device located externally of the camera.
2. Description of the Prior Art
Cameras which can incorporate a supplementary lens for varying the focal length of a regular lens, such as for instance a supplementary close-up lens which can be used to allow for the camera to take close-up pictures, are known in the photographic field. In order to compensate for parallax between the view finder and the different photographic optical systems, such conventional cameras are provided with a wedge-shaped prism which can be moved in front of the view finder optical system at the same time that the close-up lens is positioned in the photographic optical path of the regular lens, or with means to shift the field-limiting frame of the view finder. However, the provision of this wedge-shaped prism in a camera requires a significant amount of space for the wedge-shaped prism to be bodily moved within the camera and for housing the mechanism which is required for moving the wedge-shaped prism at the same time as the close-up lens is moved, thus resulting in an inability to reduce the size of the camera and hence in an inability to reduce the manufacturing cost. At the same time, when using a field-limiting frame, such a frame has to be moved within the view finder optical system, and the sizes of the optical elements which form the view finder optical system must be large enough to cover the field-limiting frame that moves as mentioned above. This results in an increase in the size of the view finder optical system. In addition, such a system suffers from the additional shortcoming that when the photographer looks through such a view finder, an unnecessary image (which in fact will not be part of the ultimate photograph) will be observable outside the field-limiting frame. This is in fact a significant drawback.
It is therefore an object of the present invention to provide a parallax compensating device which is simple in construction and which requires only a small space within the camera and therefore allows for a reduction in size and cost for the camera.
It is another object of the present invention to provide a parallax compensating device which provides automatic parallax compensation in response to a positioning of the supplementary lens in the optical path of a picture-taking lens, and which dispenses with particular prior art means to compensate for parallax, and which thereby simplifies the stand-by operation for taking a close-up picture.
It is a further object of the present invention to provide a parallax compensating device for a view finder in which an unwanted image which in fact will not be part of the photograph is not viewable outside a field-limiting frame in the view finder, but only the image of the object alone (which is to be taken as the picture) will be seen therein accurately.
It is a still further object of the present invention to provide a parallax compensating device which will clearly indicate a difference between two photographing conditions, i.e., the photographic condition in which the regular picture-taking lens is used alone, and the condition in which a supplementary lens is used in combination with the picture-taking lens.